Attending to spatial locations: a developmental study.

In 2 experiments, 7- and 8-year-old children and college students performed a letter-detection task in which reaction time was the dependent variable. Expectancy was manipulated by varying the probability the stimulus would appear at the center of an imaginary circle rather than along the perimeter. Although both age groups responded consistently faster to stimuli presented in expected locations than to stimuli presented in unexpected locations, this expectancy effect was larger for the children than it was for the college students. In a third experiment, these results were replicated using a luminance-detection task with 5-year-olds, 8-year-olds, and college students as subjects. It was concluded that children as well as adults are able to expand or contract the breadth of their attentional focus in accordance with task demands and that there is a developmental change in the efficiency with which a stimulus presented in an otherwise empty field can be located. Furthermore, it was suggested that children may be more disrupted by the occurrence of an unexpected event than adults are.